Top closing dampers

Code compliant Spark Arrestor with top closing damper
Not closing your damper is comparable to leaving a window in your home open during the winter. Over time, California homes experience earthquakes, settling of the ground they are built on as well as any number of other maladies, which causes the damper inside the chimney not to close properly, which means it is not sealing the opening completely and has become less effective in keeping your HVAC treated air contained inside your home.